1. Field of the Invention
The invention relates to an adjusting armature for the back rest of vehicle seats, in particular, of motor vehicles seats, wherein the back rest, which is optionally adjustable about a first axis of rotation in an inclined position and lockable in the adjusted inclined position by means of an adjusting device, can be folded forwardly and backwardly about a second external axis of rotation, positioned at a distance from the first axis of rotation, and is secured in its folded-back position on a locking bolt receptacle, stationarily arranged on the seat, by means of a locking bolt, engaging releasably the locking bolt receptacle and axially moveably arranged on a rotary bracket pivoting with the back rest and spring-loaded in the locking direction, and is supported by means of a stop receptacle on a stop bolt stationarily arranged on the seat.
2. Description of the Related Art
A similar device is disclosed in European patent application 0 937 603 A1. In this document an adjusting armature for the back rests of motor vehicle seats is described in which, on the one hand, the back rest is adjustable with regard to its incline about an axis and, on the other hand, is foldable about another axis. Locking is possible in the upright position of the back rest by means of a pin that is spring-loaded or receives a conical end which engages in a springy fashion a corresponding receptacle. A play-free arrangement is not ensured in all directions.
In an adjusting armature of the aforementioned kind of the present assignee, described in the German patent application 199 18 737.1-16, the armature component, which effects the adjustment and locking of the inclined back rest position and has a first axis of rotation, is arranged adjacent to a further armature component having a second axis of rotation. In order to transfer the back rest into a forwardly folded position which provides a table function, the second axis of rotation is arranged at a spacing above the first axis of rotation. For this purpose, generally on the frame of the seat part or on a locking plate fixedly connected thereto, an armature part of the armature component, which enables the inclination of the back rest in a position of use for the user of the seat, is secured detachably by means of a stop bolt and a locking bolt that is axially moveable in the locking direction and loaded by a force storing device.
Moreover, a bearing bracket of the second armature component is fixedly connected with the frame of the seat part or the locking plate and extends upwardly and past the first axis of rotation. This bearing bracket at its upper area is connected by means of an axle bolt with a rotary bracket to form a joint which provides the second axis of rotation of the adjusting armature. The rotary bracket is connected to the armature part that is detachably secured with the stop bolt and the locking bolt on the seat part and is pivotable therewith. As a result of the second axis of rotation being positioned higher, the back rest can be placed above the upholstery of the seat part in a table function position such that the backside of the back rest forms a horizontal plane without the upholstery of the back rest and of the seat part counteracting this. For securing this table function position, a pneumatic spring is arranged between the axis of rotation and the bearing bracket.
In this known solution, the axially movable locking bolt has a circular cross-section and engages in the locking situation a matching bore which, however must be slightly greater than the diameter of the locking bolt because of unavoidable tolerances. As a result of this unavoidable play, rattling cannot be prevented when the vehicle drives on bumpy roads.
It is an object of the invention to improve an adjusting armature of the aforementioned kind such that a securing or bracing is possible that eliminates play of the rotary bracket relative to the locking plate.
In accordance with the present invention, this is achieved in that the axially movable locking bolt has a guide section and a locking section and is subjected on its guide section, in addition to its axial guiding, also to a controlled rotational movement, based on which a radially changing support curve provided on the locking section can be supported on a planar support surface of the locking bolt receptacle so as to eliminate play.
By superimposing on the axially movable locking bolt a rotary movement such that its locking section with the adjustable radially changing support curve automatically readjust on a planar support surface of the locking bolt receptacle as a result of the spring loading action, a bracing that eliminates play is obtained in the locking situations so that the adjusting armature is free of rattling noises independent of its unavoidable tolerances.
For forming the radially changing support curve in connection with a support surface contacting it, the locking section of the annular pin has a periphery as follows: a first partial peripheral area extends about approximately 180xc2x0 with a constant radius and is adjoined by a peripheral area of approximately 90xc2x0 in which the support curve extends which, starting with the constant radius of the first partial peripheral area, has a continuously decreasing radial spacing from the center of the locking bolt, and then has a transition into at least one planar area which then adjoins finally the aforementioned first partial peripheral area with the constant radius. The locking bolt receptacle has, in addition to a circular circumferential area, a support surface which can be brought into contact with the support curve.
The support curve which has a continuously decreasing radial spacing from the center of the locking bolt can be designed as a logarithmic spiral with which the manufacturing tolerances and play can be compensated which do not reach the adjusting range resulting from the support curve and which are within the tolerances.
According to one embodiment of the invention, for axially guiding the locking bolt and providing a superimposed rotary movement derived from this axial movement, the guide section of the locking bolt is arranged axially slidably in a bushing secured on the rotary bracket and engages with at least one sliding block at least one sliding gate extending spirally in the bushing like a thread. In this connection, the bushing is advantageously surrounded by a trigger sleeve which has at least one guide groove ascending in the axial direction and whose slant or gradient is greater than the slant of the thread-like sliding gate of the bushing. The sliding gate is engaged by the sliding block which penetrates it and engages the guide groove of the trigger sleeve.
In order to prevent a malfunction which could possibly occur as a result of canting, according to a further embodiment of the invention the sliding gate as well as the guide groove are positioned on two locations of the bushing and the trigger sleeve which are diametrically opposite one another, wherein the sliding block is comprised of two guide pins which are arranged on the guide section of the locking bolt, penetrate through the sliding gate, and project into the guide groove. Moreover, an actuation device which is located remote from the locking mechanism for releasing the locking bolt can be realized in that the trigger sleeve has a connecting finger provided for attaching a pulling means thereto, such as a Bowden cable, for introducing a rotary movement into the trigger sleeve.
Since in the inactive position of the trigger sleeve the locking bolt projects from the bushing as a result of spring loading of the locking bolt in the locking direction, it is advantageous for the return movement of the back rest from its forwardly folded position when a guide rail is provided on the seat which projects into the pivot path of the locking bolt and has a slanted surface. This ensures that in the inactive state of the trigger sleeve the return pivot movement can be performed to such an extent until the locking bolt is able to drop into the locking bolt receptacle provided on the seat part.
Even though it is conceivable to arrange the guide rail and the locking bolt receptacle directly on the frame of the seat part, it may be advantageous for manufacturing-technological reasons when the bearing bracket together with the locking plate that is provided with the locking bolt receptacle as well as the guide rail is fixedly connected with the seat part.
In order for a safe correlation of the locking bolt to the locking bolt receptacle to be possible at the end of the return folding movement, on the one hand, and to provide a 3-point bracing of the rotary bracket relative to the seat part, on the other hand, the locking plate advantageously has underneath its locking bolt receptacle a stop for the rotary bracket and an armature part that is connected to the rotary bracket and comprises the first axis of rotation.